How can I automatically mark pool addresses down when one ISP fails with GTM acting as Link Controller with multiple ISP's?

I see an interesting option you can add to the "virtual servers" the GTM learns about from the LTM - the box is titled "Dependency List" -- From the onscreen help: "Specifies the virtual servers on which the current virtual server depends. If any of the specified servers are unavailable, the current virtual server is also listed as unavailable." This would seem to be the key. I'm guessing creating some kind of server/pool/monitoring combination on the LTM will have just one entity doing the upstream monitoring for an ISP and if that goes down the corresponding server/IP goes down on the GTM (hopefully stopping it from giving out that particular IP address) If anyone has an example of this kind of design configuration I'd love to see it.